Hi Davide,
FYI, there is a similar thread in the Rhino Mac Forum. I’m fiddling around with making a manual solution for a setback fillet, but I’m not having much luck. In another past post it looks like there was something like a solution but I couldn’t quite make out the author’s methodology. It looks like his surface continuity was really nice.
Do a Google search for setback fillet nurbs and you get all sorts of people like us discussing the problem. So far I haven’t come across any fantastic solutions. I have the VSR Shape Modeling plugin, but I haven’t played with it yet enough to make the solution work optimally (using default settings it flattens out the corner which doesn’t look good). It’s fast and pretty good, but I want as close to perfect as I can get.
I’ll post again if I can come up with anything meaningful. I’m thinking a solution looks something vaguely like this (work in progress, and it doesn’t work for tangency yet):
I’ll pick it up again tomorrow for a while.
-=André
EDIT: I fiddled around with it this morning for a while longer and I was able to get G2 continuity manually, but the surfaces were too complex and have unpleasant surface waviness. I think it’s time to finally break down and watch all the VSR youtube videos.